Alpha-olefins, especially those containing about 6 to about 20 carbon atoms, are important items of commerce, with about 1.5 million tons reportedly being produced in 1992. Alpha-olefins are also used as intermediates in the manufacture of detergents, as monomers (especially in linear low density polyethylene), and as intermediates for many other types of products. Alpha-olefins may also be employed in the oilfield drilling fluids market. The use of alpha-olefins as such, and alpha-olefins isomerized to internal olefins, has increased in recent years. As a consequence, improved methods of making these compounds are of value.
Most commercially produced alpha-olefins are made by the oligomerization of ethylene, catalyzed by various types of compounds, see for instance B. Elvers, et al., Ed. Ullmann's Encyclopedia of Industrial Chemistry, Vol. A13, VCH Verlagsgesellschaft mbH, Weinheim, 1989, p. 243-247 and 275-276, and B. Cornils, et al., Ed., Applied Homogeneous Catalysis with Organometallic Compounds, A Comprehensive Handbook, Vol. 1, VCH Verlagsgesellschaft mbH, Weinheim, 1996, p. 245-258. The major types of commercially used catalysts are alkylaluminum compounds, certain nickel-phosphine complexes, and a titanium halide with a Lewis acid such as diethylaluminum chloride (DEAC). In all of these processes significant amounts of vinylidene and/or tri-substituted and/or internal olefins and/or diolefins, can be produced depending on the carbon number of the olefin and the specific process. Since in most instances these are undesired, and often difficult to separate from the desired linear alpha-olefins, minimization of these byproducts is sought. Small, U.S. Pat. No. 6,911,505 discloses processes for the production of alpha-olefins, including dimerization and isomerization of olefins using a cobalt catalyst complex are provided herein. The olefins so produced are described in this patent as being useful as monomers in further polymerization reactions and useful as chemical intermediates.
Eaton, et al., U.S. Pat. No. 6,730,750 is directed to improved drag reducing agents and methods of forming improved drag reducing agents comprising the steps of isomerizing olefin monomers to form isomerized olefin monomers, polymerizing the isomerized olefin monomers in the presence of at least one catalyst to form a polyolefin drag reducing agent having unexpectedly superior drag reduction properties when combined with liquid hydrocarbons, such as viscous crude oil. This patent further discloses that the drag reducing agents may be introduced into conduits, such as pipelines, to increase the flow of the hydrocarbons through the conduit.